The default value of this property is an expression that evaluates to an
NSValue object containing a CGVector struct set to 0 points rightward and 0
points downward. Set this property to nil to reset it to the default value.

This attribute corresponds to the fill-translate
layout property in the Mapbox Style Specification.

You can set this property to an expression containing any of the following:

Constant CGVector values

Predefined functions, including mathematical and string operators

Conditional expressions

Variable assignments and references to assigned variables

Interpolation and step functions applied to the $zoomLevel variable

This property does not support applying interpolation or step functions to
feature attributes.